Installing the Kimberly, Part 2: Cutting The Cathedral Ceiling Box

Okay, so it took us a little longer than expected, but we got our chimney hole cut. 

Sam courageously makes the first roof puncture

It actually turned out to be a little more complicated than we had initially thought. If you want a vertical square chimney box to go through a roof panel that's on a 45-degree pitch, you can't simply hold the box flush to the panel, trace around it and cut. You have to figure out what the area of the square chimney box is on the plane of the roof panel (a rectangle), and cut that shape out of the ceiling. You also can't cut the hole perpendicular with the roof panel, but have to cut it on a 45-degree bevel from the roof (since the roof is 45-degrees off of vertical, you need to correct for that so that the cut you make is vertical), 

Fortunately our jig-saw has a bevel option, so that we can position the blade at a 45-degree angle relative to the foot. We can then hold the foot flush with the roof panel and have the blade make a vertical cut. Unfortunately, we don't have a jig-saw blade long enough to go through both  skins of our SIP. So, we cut the first one out and cleared out the polystyrene just like we did for the wheel wells. My mom was there for that part, and took a video for us. I know we've had videos of me melting the foam core of our SIPs before, but here's another one, just in case you enjoy watching the process as much as I like doing it. 

Then we were able to drill holes in the roof at the base of the hole, and from the outside measure the appropriate rectangle on the outside skin of the roof panel. Once that was cut, it was just a matter of clearing out enough foam for us to install a wooden frame inside the hole the same way the SIP manufacturers installed wooden frames inside the holes they cut for the windows. 

We called it a day after that, and tomorrow we'll frame the thing.